Method of glazing powder.



110913337 11. PATENT-ED JULY14, 1903,:

- A. I. DU PONT.

. METHOD OF GLAZING POWDER.

. AIPLIOATIOH FILED FEB. 28,1903.

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"-NO. 733,741, PATENTED JULY 14, 1903." A. I. DU PONT. v

METHOD OF GLAZING POWDER.

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PATENTBD JULY 14; 1903.

' A. I. DU PONT.

METHOD OF GLAZING POWDER.

APPLICATION FILED 1'33. 28, 1903.

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I 9 I X PATENT Patented July 14, 1903.

OFFICE.

ALFRED I. DU PONT, OF WILMINGTON, DELAWARE.

METHOD OF GLAYZIQNG POWDER.

SPECIFICATION forming part of Letters Patent N 0. 733,741, dated July14, 1903. Application filed February 28, 1903. Serial No. 145,635. (Nospecimens.)

To all whom/it mag concern:

Be it known that I, ALFRED I. DU PONT, a

citizen of the United States, residing at VVilmington, county ofNewcastle, State of Delaware, have invented certain new and usefulImprovements in Methods of Glazing Blasting-Powder, Gunpowder, and theLike; and I do hereby declare the following to be a full, clear, andexact description of the invention, such as will enable others skilledin theart to which it appertains to make and use the same.

My invention relates to the manufacture of powder, and particularly to asafe andexpeditious method for glazing grains of blasting-powder,gunpowder, and the like.

The method ordinarily employed for the glazing of blasting and similarpowders consists, primarily, in rumbling the grains in a rotating woodendrum or barrel. After the rotation of the drum has been continued forabout ten hours, at a speed consistent with safety, the friction causedby the grains rubbing against each other and against the walls of thedrum or barrel generates sufficient heat to bring to the surface themoisture contained in the grains and to drive it off in the form ofwatery vapor. The rotation of the drum or barrel is continued thereafterand a stream of air is sometimes passed through the drum for the purposeof carrying off the watery vapor and, incidentally, drying the powder.After the rotation is continued for some eight or ten hours longer aquantity of pluinbago is inserted. The drum or barrel is then rotatedfor a still further period of an hour or more, whereupon the grainsmaybe found to be glazed and polished. No glazing whatever is possiblein this operation until the grains have given. off the watery vaporreferred tothat is, the glazing operation proper does not begin untilabout ten hours after the drum or barrel has been put into rotation. Thetime required for the initial or watery-vapor generating step of theoperation so lengthens the entire process that a very considerableamount of fine dust is produced, composed of particles which are rubbedoff from the grains during the long rumblingoperations. Some of thisdust adheres to the walls of the vessel and to the grains of powder anddoes now harm; but if there is any loose dust it prevents the glazing'ofthe 'tion of the grains for that purpose.

. grains and in all cases is the source of a corresponding decrease inthe output of the process. The glazing of very small grains by the oldprocess is only practicable by first mixing them with grains of a largersize before inserting them in the drum or barrel, attempts to glaze verysmall grains alone being practically ineffectual, for the reason that somuch dust is produced in the operation as to prevent any glazingwhatever.

The purpose of my invention is to very materially shorten the periodrequired for glazing grains of powder, and especially the periodrequired for the initial step of the operation, while still preservingand even enhancing the safety of the operation as a whole. By means ofmy improvements I am enabled to cut down the duration of the glazingprocess to less than one-third of the time required under the formerpractice, and I am also enabled successfully to glaze powders of a muchsmaller size than have heretofore been successfully glazed. I alsoeffect a notable economy in the horse-power employed for rumbling agiven quantity of powder, obtain an increased output owing to the lesserquantity of dust producedand the rapidity of the operation, and amenabled to successfully and safely remove the dust lining incident tothe practice of the invention, as will.

. hereinafter more fully appear.

In carrying out my invention I substitute for the usual wooden drum orbarrel a metal barrel provided with a jacket into which steam isadmitted during the initial stage of the rumbling operation for thepurpose bringing the moisture of the grains to the surface promptlyinstead of depending upon the fric- The watery vapor given ofi by thegrains is confined within the barrel until the grains are brought to theglazing-point, whereupon the flow of steam to the jacket is interruptedand the temperature of the jacket correspondingly lowered, so that asufficient quantity of the watery vapor'is condensed thereon to collectthe dust and cause it to adhere to the inner surface of the drum orbarrel, thus leaving the powder-grains clean or free from dust.

or barrel, and at the same time causing a body of cold air to passthrough it, which cold air expels any remaining watery vapor, so thatthe product may be obtained in as dry a condition as desired.

In order to polish the powder, pulverized plumbago may be placed in thedrum or barrel during the final stage of the operation.

In the accompanying drawings I have illustrated apparatus suitable forthe practice of my invention and which I prefer to use, although it willbe understood that I do not intend to limit myself to the employment ofthe specific rumble shown.

In the drawings, Figure 1 represents in longitudinal section the mainbody portion and journals of an apparatus suitable for the practice ofmy invention. Fig. 2 represents a like View, on a larger scale, of thesteam and air outlet end of the apparatus. Fig. 3 represents an endelevation thereof; and Fig. 4 represents in longitudinal section, on astill larger scale, the steam and air inlet end of the apparatus. Fig. 5represents the inlet-joint partly disassembled. Fig. 6 represents acentral section through the drum.

Referring to the drawings, it will be noted that the main heads of theapparatus consist of stout castings having inner flanges a a, over whichfits the metallic shell A, and flanges b 1), against which abut thesheetmetal end plates 13 O. The castings are provided with central hubsD E, forming journals for the apparatus, which journals are perforatedcentrally, as shown at d d, for a purpose hereinafter described.

In order to provide a steam-jacket for the apparatus, I inclose theinner shell A within an outer shell F, said outer shell being centeredby means of centering-rings f. The steam-space 9 thus providedcommunicates, by means of piping h h, with the steam-channels i 2" ofthe journal D, so that by connecting the said channels to a suitablesource of steam-supply a current of steam may be conducted into thesteam-space 9. At the opposite end of the drum similar piping 7&2 it(see particularly Figs. 2 and 3) conveys the steam and condensed waterfrom the steamspace 9 to the outlet-channels i of the journal E. Thepiping 7L2 7L3 is not shown in Fig. l for the reason that it lies in aplane at right angles to the plane in which is located the piping 7L h,as will be readily understood.

In order to permit the barrel or rumble and its journals to rotate,while still maintaining steam-tight connection with the steam supply andexhaust conduits, I provide suitable rotatory joints at the ends of thejournals D and E.

The rotatory joint connecting the stationary steam-in let conduit Gwiththe journal D is shown in Figs. 4c and 5. It consists, primarily, of aplate 7t, attached to the end of the journal by countersunk screws andconnected by bolts and nuts, as shown, to a plate a, having an air-inletpipe at registering with and forming a continuation of the channel (Z ofExterior to the plate a is a the journal.

grooved ring-plate r, secured by countersunk screws to the plate a, thusholding the ringplates p and 0". An annular stationary plate 5-, havingan aperatu re s communicating with the steam-supply conduit G, closesthe end of the plate 0". It will be evident that in this constructionthe conduit G and plate 3 remain stationary while the remaining partsrevolve, a steam-tight connection being constantly maintained and thesteam being freely supplied to both channels 1? e'. At the opposite orexhaust journal E, I preferably employ a simpler arrangement, for thereason that the pressure is lower. In this instance (see Figs. 2 and 3)the joint may conveniently consist of a single annular chamber L,secured to the end of the journal E so as to revolve therewith, with theexception of the two-part periphery t, which is stationary and withinwhich the circular end walls of the chamber rotate. A stationarycollecting-hood 4) conveys the exhaust-steam from the annular chamber,which latter is likewise provided with a pipe w, forming a continuationof the outlet channel (7/, which leads from the interior of the drum orbarrel.

By the construction of apparatus described it is evident that I canmaintain a substantially constant temperature within the barrel orrumble, the continuously-moving body of steam serving not only tomaintain a given temperature within the barrel, but to carry oif anyexcess of temperature which may be generated therein during any stage ofthe operation.

In the practice of my invention I insert the powder to be glazed withinthe drum or barrel through the inlet-opening kfml then close theinlet-openin g and rotate the barrel at a speed of about twentyrevolutions per minute, at the same time causing a current of steam at atemperature of about 212 Fahrenheit to pass continuously into thesteam-space of the barrel and outwardly therefrom. The heat furnished bythe steam soon raises the temperature of the grains to a point at whichthe moisture rapidly comes from the interior of the grains to the outersurface thereof. When the temperature of the grains is raised to from160 to 170 Fahrenheit, moisture equal in amount to about from one tothree per cent. of their weight comes to the surface of the grains andis given off in the form of watery vapor. This watery vapor is confinedwithin the interior of the barrel and accumulates in sul'ficientquantity therein at about the end of three-quarters of an hour from thebeginning of the rotation of the barrel, whereupon the admission ofsteam to the steam-space of the barrel is cut off and the barrel beginsto cool. As the barrel cools the watery vapor within it condenses on theinner surface of the shell A and takes up the dust produced by thefriction of the powdergrains upon each other, thus separating the dustfrom the grains and depositing it in a layer over the entire innersurface of the rumble. This con,-

drum is continued until the desired amount" of moisture has been drivenoff. At the proper time pulverized plumbago for polishing the powder isplaced in the rumble and after revolving the rumble for one or morehours longer, depending on the size and kind of powder, the operation iscompleted, the powder-grains being both glazed and dry.

I have already directed attention to the fact that the'steam admitted tothe jacket during the first hour of the rumbling operation is atboiler-pressuresay 212 Fahrenheit. This is the stage of the rumblingoperation during which there is some danger of an excessive rise intemperature beyond the limitations of safety. It is not desirable,however, that the powder-grains -should attain too high a temperature;and I find in practice that, should the mass of powder approach thetemperature of 212 any increasein temperaturedue rumble until the grainsgive oif watery vapors,

to friction'of the grains upon each other is obviated .by'reason ofv thecapacity of the steam to conduct away the excess of .heat as 1 fast asit is generated. In practice it is found that by using low-pressuresteam 210 Fahrenheit is the highest temperature that can be realizedwithin the rumble when the drum is revolving at the rate of twentyrevolutions per minute, this maximum limit serving as an absolutesafeguard to the'operation- At the termination of the operation andafter the removal of the glazed grains from the barrel the dust layerdeposited upon the inner surface of the barrel is to be removed.v

This dust layer is of such thickness and solidity as to form a tubularlining to the barrel. A safe and convenientway' of removing it consistsin readmitting steam into the jacket, thereby causing an expansionthereof sufficient to entirely detach the dust lining. Steam is thenadmitted into the interior of thedust tube thus detached, so as tosoften and break downthe arch of the tube. The barrel may now be rotatedfor a few minutes, whereupon the detached dust lining will break up andpass through the opening 76.

The apparatus herein described is thesubject of another application forpatent, Serial No. 145,536, filed of even dateherewith.

Having thus described my invention, what I claim is' 1. The method ofglazing grains of powder, which consists in rumbling the grains, withthe incidental production of. dust, applying heat to the inner lining orperiphery of the confining the watery vapors within the rumble, thenlowering the temperature of the inner lining or periphery and condensingthe watery vapors thereon in quantity sufficient to take up the dust,and continuing the rumbling until the desired glazing isobtained;substantially as described.

2. The method of glazing grains of powder, which consists in rumblingthe grains, with the incidental production of dust, applying heat to theinner lining or periphery of the rumble, and until the grains give offwatery vapors, confining the watery vapors within the rumble, thenlowering the temperature of the inner lining or periphery and condensingthe watery vapors thereon in quantity sufficient to take up the dust,and continuing the rumbling until the desired glazing is obtained, inthe meantime hastening the termination of the operation by expelling anyremaining watery vapor from the rumble; substantially as described. 7

3. The method of glazing grains of powder, which consists in rumblingthe grains, with the incidental production of dust, applying heat to theinner lining or periphery of the rumble, and until the grains give offwatery vapors, confining the watery vapors within the rumble, thenlowering the temperature of the inner lining or periphery andcondensing. the watery vapors thereon in quantity sufficient to take upthe dust, and continuing the rumbling until the desired glazing isobtained,

in the meantime hastening the terminationof the operation by expellingany remaining watery vapor from the rumble by means of a current of air,and continuing the passage of the airthrough the rumble until the grainsare dry.

1. In the method of glazing grains of powder by rumbling, passing acontinuous current of low-pressure steam in contact with the outerperiphery of the rumble duringthe initial or watery-vapor stage of theoperation; substan tially as described.

5. The method of removing the dust-lining from a glazing-rumble, whichconsists in expanding the rumble, so as to detach the dustlining tubetherefrom, and then breaking down the detached tube; substantially asdescribed.

IIO

' 6. The method of removing the dust-lining from a glazing-rumble, whichconsists in expanding the rumble, so as to detach the dustlining tubetherefrom, and then softening and breaking down the detached tube byfirst admitting a'current of steam into its interior;

substantially as described.

" In testimony whereof I affix my signature in presence of twowitnesses.

ALFRED I. DUPONT.

lVitnesses V G. A. MADDOX, WM. L. SCOTT.

